Exposure apparatus and method for producing device

ABSTRACT

An exposure apparatus exposes a substrate P by locally filling a side of an image plane of a projection optical system PL with a liquid  50  and projecting an image of a pattern onto the substrate P through the liquid  50  and the projection optical system PL. The exposure apparatus includes a recovery unit  20  which recovers the liquid  50  outflowed to the outside of the substrate P. When the exposure process is performed in accordance with the liquid immersion method, the pattern can be transferred accurately while suppressing any environmental change even when the liquid outflows to the outside of the substrate.

CROSS-REFERENCE

This is a Division of U.S. patent application Ser. No. 11/141,090 filedJun. 1, 2005, which in turn is a Continuation of InternationalApplication No. PCT/JP03/015666 filed Dec. 8, 2003 claiming theconventional priority of Japanese patent Application Nos. 2002-357958filed on Dec. 10, 2002 and 2003-296491 filed on Aug. 20, 2003. Thedisclosures of these prior applications are incorporated by reference intheir entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exposure apparatus for performingthe exposure with an image of a pattern projected by a projectionoptical system in a state in which a space on a side of an image planeof the projection optical system is locally filled with a liquid. Thepresent invention also relates to a method for producing a device byusing the exposure apparatus.

2. Description of the Related Art

Semiconductor devices and liquid crystal display devices are producedwith the so-called photolithography technique in which a pattern formedon a mask is transferred onto a photosensitive substrate. The exposureapparatus, which is used in the photolithography step, includes a maskstage for supporting the mask and a substrate stage for supporting thesubstrate. The pattern on the mask is transferred onto the substrate viaa projection optical system while successively moving the mask stage andthe substrate stage. In recent years, it is demanded to realize thehigher resolution of the projection optical system in order to respondto the further advance of the higher integration of the device pattern.As the exposure wavelength to be used is shorter, the resolution of theprojection optical system becomes higher. As the numerical aperture ofthe projection optical system is larger, the resolution of theprojection optical system becomes higher. Therefore, the exposurewavelength, which is used for the exposure apparatus, is shortened yearby year, and the numerical aperture of the projection optical system isincreased as well. The exposure wavelength, which is dominantly used atpresent, is 248 nm of the KrF excimer laser. However, the exposurewavelength of 193 nm of the ArF excimer laser, which is shorter than theabove, is also practically used in some situations. When the exposure isperformed, the depth of focus (DOF) is also important in the same manneras the resolution. The resolution R and the depth of focus δ arerepresented by the following expressions respectively.R=k ₁ •λ/NA  (1)δ=±k ₂ •/NA ²  (2)

In the expressions, λ represents the exposure wavelength, NA representsthe numerical aperture of the projection optical system, and k₁ and k₂represent the process coefficients. According to the expressions (1) and(2), the following fact is appreciated. That is, when the exposurewavelength λ is shortened and the numerical aperture NA is increased inorder to enhance the resolution R, then the depth of focus δ isnarrowed.

If the depth of focus δ is too narrowed, it is difficult to match thesubstrate surface with respect to the image plane of the projectionoptical system. It is feared that the margin is insufficient during theexposure operation. Accordingly, the liquid immersion method has beensuggested, which is disclosed, for example, in International PublicationNo. 99/49504 as a method for substantially shortening the exposurewavelength and widening the depth of focus. In this liquid immersionmethod, the space between the lower surface of the projection opticalsystem and the substrate surface is filled with a liquid such as wateror any organic solvent to utilize the fact that the wavelength of theexposure light beam in the liquid is 1/n as compared with that in theair (n represents the refractive index of the liquid, which is about 1.2to 1.6 in ordinary cases) so that the resolution is improved and thedepth of focus is magnified about n times.

The conventional technique as described above involves the followingproblem. The conventional technique is constructed such that the space,which is disposed between the substrate (wafer) and the lower surface onthe side of the image plane of the projection optical system, is locallyfilled with the liquid. When a shot area, which is positioned in thevicinity of the center of the substrate, is subjected to the exposure,the liquid does not outflow to the outside of the substrate. However, asschematically shown in FIG. 14, when it is intended to expose an edgearea E of the substrate P by moving the circumferential area (edge area)E of the substrate P to the projection area 100 of the projectionoptical system, the liquid outflows to the outside of the substrate P.If the outflowed liquid is left to stand, the environment (for example,humidity), in which the substrate P is placed, is consequently varied tocause, for example, the change of the refractive index on the opticalpath of the interferometer for measuring the position information aboutthe substrate stage for holding the substrate P and/or on the opticalpath of the detecting light beam of each of various optical detectingdevices. As a result, it is feared that any desired pattern transferaccuracy cannot be obtained. Further, an inconvenience also arises, forexample, such that any rust appears due to the outflowed fluid onmechanical parts or the like arranged around the substrate stage forsupporting the substrate P. It is also conceived that the liquid isprevented from any outflow by omitting the exposure for the edge area Eof the substrate P. However, if the pattern is not formed by applyingthe exposure process to the edge area E as well, another problem arisesas follows. That is, the substrate P as the wafer abuts against thepolishing surface of the CMP apparatus in an unbalanced manner, forexample, in the CMP (chemical mechanical polishing) process as thedownstream step, and it is impossible to perform any satisfactorypolishing. Further, if the outflowed liquid makes inflow into the tubeof the vacuum system (suction system), it is also feared that the vacuumpump, which serves as the vacuum source, may be damaged or broken down.

SUMMARY OF THE INVENTION

The present invention has been made taking the foregoing circumstancesinto consideration, an object of which is to provide an exposureapparatus and an exposure method in which a pattern can be transferredaccurately when an exposure process is performed while filling a spacebetween a projection optical system and a substrate with a liquid, and amethod for producing a device in which the exposure apparatus is used.

In order to achieve the object as described above, the present inventionadopts the following constructions.

According to a first aspect of the present invention, there is providedan exposure apparatus for exposing a substrate by transferring an imageof a pattern through a liquid onto the substrate, comprising:

-   -   a projection optical system which projects the image of the        pattern onto the substrate; and    -   a recovery unit which recovers the liquid outflowed to outside        of the substrate.

According to the present invention, even when the liquid outflows to theoutside of the substrate, then the outflowed liquid is recovered by therecovery unit without being left to stand. Therefore, the variation ofthe environment in which the substrate is placed is suppressed. Further,the occurrence of the inconvenience is also suppressed, which would beotherwise caused such that any rust or the like appears on mechanicalparts disposed around the substrate stage for supporting the substrate.Therefore, it is possible to accurately transfer the pattern to thesubstrate, and it is possible to produce a device having a high patternaccuracy.

According to a second aspect of the present invention, there is providedan exposure apparatus for exposing a substrate by transferring an imageof a pattern through a liquid onto the substrate, comprising:

-   -   a projection optical system which projects the image of the        pattern onto the substrate;    -   a liquid supply mechanism which supplies the liquid above the        substrate; and    -   a recovery unit which recovers the liquid supplied from the        liquid supply mechanism,    -   wherein the recovery unit does not perform the recovering above        the substrate.

According to the present invention, the liquid can be recovered (sucked)without performing the recovery (suction) above the substrate (fromabove the substrate). Therefore, it is possible to avoid the occurrenceof the sound and the vibration during the exposure for the substrate.Further, the liquid, which outflows to the outside of the substrate, isrecovered by the recovery unit. Therefore, it is possible to avoid thevariation of the environment in which the substrate is placed and theoccurrence of any rust or the like on mechanical parts. Therefore, it ispossible to accurately form the pattern on the substrate, and it ispossible to produce a device having a high pattern accuracy.

According to a third aspect of the present invention, there is providedan exposure apparatus for exposing a substrate by transferring an imageof a pattern through a liquid onto the substrate, comprising:

-   -   a projection optical system which projects the image of the        pattern onto the substrate;    -   a suction system which has a suction port; and    -   a recovery unit which recovers the liquid sucked through the        suction port.

According to the present invention, for example, even when the liquidoutflows, and the liquid inflows into the suction port of the suctionsystem, then the liquid is recovered, and the vacuum source, whichserves as the source of the suction, is prevented from any inflow of theliquid. Therefore, even when the liquid immersion exposure is performed,the function of the suction system is guaranteed. It is possible toproduce a device by reliably exposing the substrate with the highlyaccurate pattern.

According to a fourth aspect of the present invention, there is providedan exposure apparatus for exposing a substrate by transferring an imageof a pattern through a liquid onto the substrate, comprising:

-   -   a projection optical system which projects the image of the        pattern onto the substrate;    -   a substrate stage which holds the substrate; and    -   a recovery unit which recovers the liquid and at least a part of        which is provided on the substrate stage. The exposure apparatus        of the present invention makes it possible to avoid the        variation of the environment in which the substrate is placed        and the occurrence of any rust or the like of mechanical parts.

According to a fifth aspect of the present invention, there is providedan exposure method for exposing a substrate by transferring an image ofa predetermined pattern onto the substrate with a projection opticalsystem, comprising:

-   -   supplying a liquid above the substrate to a space between the        projection optical system and the substrate;    -   recovering the supplied liquid from a position which is outside        the substrate and which is lower than that of the substrate; and    -   exposing the substrate during a period in which the liquid is        supplied and recovered.

In the exposure method of the present invention, the liquid is suppliedabove the substrate, and the liquid is recovered below the position atwhich the substrate is held when the liquid immersion exposure isperformed. Therefore, it is possible to effectively avoid the occurrenceof the sound and the vibration during the exposure of the substrate.

According to still another aspect of the present invention, there isprovided a method for producing a device by using the exposure apparatusaccording to any one of the first to fourth aspects described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic arrangement illustrating an embodiment of theexposure apparatus of the present invention.

FIG. 2 shows a positional relationship among a tip of a projectionoptical system, a liquid supply unit, and a liquid recovery unit.

FIG. 3 shows an exemplary arrangement of supply nozzles and recoverynozzles.

FIG. 4 shows an exemplary arrangement of supply nozzles and recoverynozzles.

FIG. 5 shows a perspective view illustrating an embodiment of a recoveryunit.

FIG. 6 shows a magnified sectional view illustrating major partsdepicting the embodiment of the recovery unit.

FIG. 7 shows a magnified sectional view illustrating major partsdepicting another embodiment of a recovery unit.

FIG. 8 shows a perspective view illustrating still another embodiment ofa recovery unit.

FIGS. 9A and 9B show schematic sectional views illustrating stillanother embodiment of a recovery unit.

FIGS. 10A and 10B show schematic sectional views illustrating stillanother embodiment of a recovery unit.

FIG. 11 shows another embodiment of the operation for recovering theliquid by using a recovery unit.

FIG. 12 shows still another embodiment of the operation for recoveringthe liquid by using a recovery unit.

FIG. 13 shows a flow chart illustrating exemplary steps for producing asemiconductor device.

FIG. 14 illustrates the problem involved in the conventional technique.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

An explanation will be made below about the exposure apparatus and themethod for producing the device according to the present invention withreference to the drawings. However, the present invention is not limitedthereto. FIG. 1 shows a schematic arrangement illustrating an embodimentof the exposure apparatus of the present invention.

First Embodiment

With reference to FIG. 1, an exposure apparatus EX includes a mask stageMST which supports a mask M, a substrate stage PST which supports asubstrate P, an illumination optical system IL which illuminates, withan exposure light beam EL, the mask M supported by the mask stage MST, aprojection optical system PL which performs projection exposure for thesubstrate P supported by the substrate stage PST with an image of apattern of the mask M illuminated with the exposure light beam EL, aliquid supply unit 1 which supplies a liquid 50 onto the substrate P, arecovery unit 20 which recovers the liquid 50 outflowed to the outsideof the substrate P, and a control unit CONT which collectively controlsthe overall operation of the exposure apparatus EX.

The embodiment of the present invention will now be explained asexemplified by a case of the use of the scanning type exposure apparatus(so-called scanning stepper) as the exposure apparatus EX in which thesubstrate P is exposed with the pattern formed on the mask M whilesynchronously moving the mask M and the substrate P in mutuallydifferent directions (opposite directions) in the scanning directions.In the following explanation, the Z axis direction is the directionwhich is coincident with the optical axis AX of the projection opticalsystem PL, the X axis direction is the synchronous movement direction(scanning direction) for the mask M and the substrate P in the planeperpendicular to the Z axis direction, and the Y axis direction is thedirection (non-scanning direction) perpendicular to the Z axis directionand the Y axis direction. The directions about the X axis, the Y axis,and the Z axis are designated as θX, θY, and θZ directions respectively.The term “substrate” referred to herein includes those obtained byapplying a resist on a semiconductor wafer, and the term “mask” includesa reticle formed with a device pattern subjected to the reductionprojection onto the substrate.

The illumination optical system IL is used so that the mask M, which issupported on the mask stage MST, is illuminated with the exposure lightbeam EL. The illumination optical system IL includes, for example, anexposure light source, an optical integrator which uniformizes theilluminance of the light flux radiated from the exposure light source, acondenser lens which collects the exposure light beam EL supplied fromthe optical integrator, a relay lens system, and a variable fielddiaphragm which sets the illumination area on the mask M illuminatedwith the exposure light beam EL to be slit-shaped. The predeterminedillumination area on the mask M is illuminated with the exposure lightbeam EL having a uniform illuminance distribution with the illuminationoptical system IL. Those usable as the exposure light beam EL radiatedfrom the illumination optical system IL include, for example, emissionlines (g-ray, h-ray, i-ray) in the ultraviolet region radiated, forexample, from a mercury lamp, far ultraviolet light beams (DUV lightbeams) such as the KrF excimer laser beam (wavelength: 248 nm), andvacuum ultraviolet light beams (VUV light beams) such as the ArF excimerlaser beam (wavelength: 193 nm) and the F₂ laser beam (wavelength: 157nm). In this embodiment, the ArF excimer laser beam is used.

The mask stage MST supports the mask M. The mask stage MST istwo-dimensionally movable in the plane perpendicular to the optical axisAX of the projection optical system PL, i.e., in the XY plane, and it isfinely rotatable in the θZ direction. The mask stage MST is driven by amask stage-driving unit MSTD such as a linear motor. The maskstage-driving unit MSTD is controlled by the control unit CONT. Theposition in the two-dimensional direction and the angle of rotation ofthe mask M on the mask stage MST are measured in real-time by a laserinterferometer. The result of the measurement is outputted to thecontrol unit CONT. The control unit CONT drives the mask stage-drivingunit MSTD on the basis of the result of the measurement obtained by thelaser interferometer to thereby position the mask M supported on themask stage MST.

The projection optical system PL projects the pattern on the mask M ontothe substrate P at a predetermined projection magnification β to performthe exposure. The projection optical system PL includes a plurality ofoptical elements (lenses). The optical elements are supported by abarrel PK as a metal member. In this embodiment, the projection opticalsystem PL is a reduction system having the projection magnification βwhich is, for example, ¼ or ⅕. The projection optical system PL may beany one of the 1× magnification system and the magnifying system. Theoptical element (lens) 60 is exposed from the barrel PK on the side ofthe tip (on the side of the substrate P) of the projection opticalsystem PL of this embodiment. The optical element 60 is provideddetachably (exchangeably) with respect to the barrel PK.

The substrate stage PST supports the substrate P. The substrate stagePST includes a Z stage 51 which holds the substrate P by the aid of asubstrate holder, an XY stage 52 which supports the Z stage 51, and abase 53 which supports the XY stage 52. The substrate stage PST isdriven by a substrate stage-driving unit PSTD such as a linear motor.The substrate stage-driving unit PSTD is controlled by the control unitCONT. By driving the Z stage 51, the substrate P, which is held on the Zstage 51, is subjected to the control of the position (focus position)in the Z axis direction and the positions in the θX and θY directions.By driving the XY stage 52, the substrate P is subjected to the controlof the position in the XY directions (position in the directionssubstantially parallel to the image plane of the projection opticalsystem PL). That is, the Z stage 51 controls the focus position and theangle of inclination of the substrate P so that the surface of thesubstrate P is adjusted to match the image plane of the projectionoptical system PL in accordance with the autofocus system and theautoleveling system. The XY stage 52 positions the substrate P in the Xaxis direction and the Y axis direction. It goes without saying that theZ stage and the XY stage may be provided as an integrated body.

A movement mirror 54, which is movable together with the substrate stagePST with respect to the projection optical system PL, is provided on thesubstrate stage PST (Z stage 51). A laser interferometer 55 is providedat a position opposed to the movement mirror 54. The angle of rotationand the position in the two-dimensional direction of the substrate P onthe substrate stage PST are measured in real-time by the laserinterferometer 55. The result of the measurement is outputted to thecontrol unit CONT. The control unit CONT drives the substratestage-driving unit PSTD on the basis of the result of the measurement ofthe laser interferometer 55 to thereby position the substrate Psupported on the substrate stage PST.

In this embodiment, the liquid immersion method is applied in order thatthe resolution is improved by substantially shortening the exposurewavelength and the depth of focus is substantially widened. Therefore,the space between the surface of the substrate P and the tip surface(lower surface) 7 of the optical element (lens) 60 of the projectionoptical system PL on the side of the substrate P is filled with thepredetermined liquid 50 at least during the period in which the image ofthe pattern on the mask M is transferred onto the substrate P. Asdescribed above, the lens 60 is exposed on the tip side of theprojection optical system PL, and the liquid 50 is supplied to makecontact with only the lens 60. Accordingly, the barrel PK composed ofthe metal is prevented from any corrosion or the like. Further, the tipsurface 7 of the lens 60 is sufficiently smaller than the substrate Pand the barrel PK of the projection optical system PL, so that theliquid 50 is allowed to make contact with only the lens 60 as describedabove. Therefore, the side of the image plane of the projection opticalsystem PL is locally filled with the liquid 50. That is, the liquidimmersion portion, which is disposed between the projection opticalsystem PL and the substrate P, is sufficiently smaller than thesubstrate P. In this embodiment, pure water is used for the liquid 50.The exposure light beam EL, which is not limited to only the ArF excimerlaser beam, can be transmitted through pure water, even when theexposure light beam EL is, for example, the emission line (g-ray, h-ray,i-ray) in the ultraviolet region radiated, for example, from a mercurylamp or the far ultraviolet light beam (DUV light beam) such as the KrFexcimer laser beam (wavelength: 248 nm).

The exposure apparatus EX includes a liquid supply unit 1 which suppliesthe predetermined liquid 50 to the space 56 between the substrate P andthe tip surface (end surface of the lens 60) 7 of the projection opticalsystem PL, and a liquid recovery unit 2 as a second recovery unit whichrecovers the liquid 50 from the space 56, i.e., the liquid 50 on thesubstrate P. The liquid supply unit 1 is provided to locally fill theside of the image plane of the projection optical system PL with theliquid 50. The liquid supply unit 1 includes, for example, a tank foraccommodating the liquid 50, a pressurizing pump, and atemperature-adjusting unit for adjusting the temperature of the liquid50 supplied to the space 56. One end of a supply tube 3 is connected tothe liquid supply unit 1. Supply nozzles 4 are connected to the otherend of the supply tube 3. The liquid supply unit 1 supplies the liquid50 to the space 56 through the supply tube 3 and the supply nozzles 4.

The liquid recovery unit 2 includes, for example, a suction pump, and atank for accommodating the recovered liquid 50. One end of a recoverytube 6 is connected to the liquid recovery unit 2. Recovery nozzles 5are connected to the other end of the recovery tube 6. The liquidrecovery unit 2 recovers the liquid 50 from the space 56 through therecovery nozzles 5 and the recovery tube 6. When the space 56 is filledwith the liquid 50, then the control unit CONT drives the liquid supplyunit 1 so that the liquid 50, which is in a predetermined amount perunit time, is supplied to the space 56 through the supply tube 3 and thesupply nozzles 4, and the control unit CONT drives the liquid recoveryunit 2 so that the liquid 50, which is in a predetermined amount perunit time, is recovered from the space 56 through the recovery nozzles 5and the recovery tube 6. Accordingly, the liquid 50 is retained in thespace 56 between the substrate P and the tip surface 7 of the projectionoptical system PL, and thus the liquid immersion portion is formed. Inthis arrangement, the control unit CONT is capable of arbitrarilysetting the liquid supply amount per unit time with respect to the space56 by controlling the liquid supply unit 1. Further, the control unitCONT is capable of arbitrarily setting the liquid recovery amount perunit time from the substrate P by controlling the liquid recovery unit2.

FIG. 2 shows a partial magnified view of FIG. 1 illustrating, forexample, the lower portion of the projection optical system PL of theexposure apparatus EX, the liquid supply unit 1, and the liquid recoveryunit 2. In FIG. 2, the lens 60, which is disposed at the lowest end ofthe projection optical system PL, is formed to have a rectangular shapewhich is long in the Y axis direction (non-scanning direction) exceptfor only the portion required for the end portion 60A in the scanningdirection. During the scanning exposure, a pattern image of a part ofthe mask M is projected onto the rectangular projection area disposedjust under the end portion 60A. The mask M is moved at the velocity V inthe −X direction (or in the +X direction) with respect to the projectionoptical system PL, in synchronization with which the substrate P ismoved at the velocity β•V (β is the projection magnification) in the +Xdirection (or in the −X direction) by the aid of the XY stage 52. Afterthe completion of the exposure for one shot area, the next shot area ismoved to the scanning start position in accordance with the stepping ofthe substrate P. The exposure process is successively performedthereafter for each of the shot areas in accordance with thestep-and-scan system. This embodiment is designed so that the liquid 50is allowed to flow in the movement direction of the substrate P alongwith the movement direction of the substrate P.

FIG. 3 shows the positional relationship among the end portion 60A ofthe lens 60 of the projection optical system PL, the supply nozzles 4(4A to 4C) for supplying the liquid 50 in the X axis direction, and therecovery nozzles 5 (5A, 5B) for recovering the liquid 50. In FIG. 3, theend portion 60A of the lens 60 has a rectangular shape which is long inthe Y axis direction. The three supply nozzles 4A to 4C are arranged onthe side in the +X direction, and the two recovery nozzles 5A, 5B arearranged on the side in the −X direction so that the end portion 60A ofthe lens 60 of the projection optical system PL is interposed thereby.The supply nozzles 4A to 4C are connected to the liquid supply unit 1through the supply tube 3, and the recovery nozzles 5A, 5B are connectedto the liquid recovery unit 2 through the recovery tube 6. Further, thesupply nozzles 8A to 8C and the recovery nozzles 9A, 9B are arranged atpositions obtained by rotating, by substantially 180°, the positions ofthe supply nozzles 4A to 4C and the recovery nozzles 5A, 5B about thecenter of the end portion 60A. The supply nozzles 4A to 4C and therecovery nozzles 9A, 9B are alternately arranged in the Y axisdirection. The supply nozzles 8A to 8C and the recovery nozzles 5A, 5Bare alternately arranged in the Y axis direction. The supply nozzles 8Ato 8C are connected to the liquid supply unit 1 through the supply tube10. The recovery nozzles 9A, 9B are connected to the liquid recoveryunit 2 through the recovery tube 11.

As shown in FIG. 4, the supply nozzles 13, 14 and the recovery nozzles15, 16 may be also provided on the both sides of the end portion 60A inthe Y direction so that the end portion 60A is intervened between thesupply nozzles 13, 14 and the recovery nozzles 15, 16. The supplynozzles and the recovery nozzles can be used to stably supply the liquid50 to the space between the projection optical system PL and thesubstrate P even during the movement of the substrate P in thenon-scanning direction (Y axis direction) when the stepping movement isperformed.

The shape of the nozzle is not specifically limited. For example, twopairs of the nozzles may be used to supply or recover the liquid 50 forthe long side of the end portion 60A. In this arrangement, the supplynozzles and the recovery nozzles may arranged while being alignedvertically in order that the liquid 50 can be supplied and recovered inany one of the directions of the +X direction and the −X direction.

Next, an explanation will be made with reference to FIGS. 5 and 6 aboutan embodiment of the recovery unit 20 for recovering the liquidoutflowed to the outside of the substrate P. FIG. 5 shows a perspectiveview illustrating the Z stage 51 (substrate stage PST), and FIG. 6 showsa magnified sectional view illustrating major parts.

In FIGS. 5 and 6, the recovery unit 20 is provided with aliquid-absorbing member 21 which is arranged around the substrate P heldby a holder 57 on the Z stage 51. The liquid-absorbing member 21 is anannular member having a predetermined width. The liquid-absorbing member21 is arranged in a groove 23 which is formed annularly on the Z stage51. A flow passage 22, which is continued to the groove 23, is formed inthe Z stage 51. The bottom of the liquid-absorbing member 21 arranged inthe groove 23 is connected to the flow passage 22. The liquid-absorbingmember 21 is composed of, for example, a porous material such as porousceramics. Alternatively, sponge as a porous material may be used as amaterial for forming the liquid-absorbing member 21. Theliquid-absorbing member 21 composed of the porous material is capable ofretaining the liquid in a predetermined amount.

An auxiliary plate 59 having a predetermined width, which surrounds theouter circumference of the substrate P, is provided between theliquid-absorbing member 21 and the substrate P held by the holder 57 onthe Z stage 51. The surface height of the auxiliary plate 59 is set tobe approximately coincident with the surface height of the substrate Pheld by the holder 57 of the Z stage 51. The liquid 50 can becontinuously retained between the substrate P and the lens 60 of theprojection optical system PL by the aid of the auxiliary plate 59, evenwhen the circumferential area (edge area) E of the substrate P ispositioned under the lens 60 of the projection optical system PL. Theliquid-absorbing member 21 having the predetermined width, which isarranged to surround the outer circumference of the auxiliary plate 59,functions to absorb (recover) the liquid 50 which cannot be fullyrecovered by the liquid recovery unit 2 as the second recovery unit andwhich outflows to the outside of the auxiliary plate 59.

The holder 57 has a plurality of projections 58 provided to support theback surface of the substrate P in a circular recess which is formed toapproximately the same size as that of the substrate P on the Z stage51. Attraction holes 24, which serve to attract and hold the substrateP, are provided for the projections 58 respectively. The respectiveattraction holes 24 are connected to a flow passage 25 which is formedin the Z stage 51. A plurality of liquid recovery holes 46 are providedin the vicinity of the outermost circumference of the holder 57(circular recess). The liquid recovery holes 46 are connected to theflow passage 22 which is connected to the liquid-absorbing member 21.Alternatively, another flow passage, which is different from the flowpassage 22 connected to the liquid-absorbing member 21 (groove 23), maybe provided to make connection to the liquid recovery holes 46.

The flow passage 22, which is connected to the liquid-absorbing member21 and the liquid recovery holes 46 respectively, is connected to oneend of a tube passage 26 which is provided outside the Z stage 51. Onthe other hand, the other end of the tube passage 26 is connected to apump 29 as a suction unit via a first tank 27 and a valve 28 providedoutside the Z stage 51. The flow passage 25, which is connected to theattraction holes 24, is connected to one end of a tube passage 30 whichis provided outside the Z stage 51. On the other hand, the other end ofthe tube passage 30 is connected to a pump 33 as a suction unit via asecond tank 31 and a valve 32 provided outside the Z stage 51. Theliquid, which outflows to the outside of the substrate P, is recoveredtogether with the surrounding gas (air) from the liquid-absorbing member21 and the liquid recovery holes 46. The liquid, which leaks into theback surface side of the substrate P, is recovered together with thesurrounding gas (air) from the attraction holes 24. The method forrecovering the liquid as described above will be explained in detaillater on. The liquid (water), which is recovered from theliquid-absorbing member 21, the liquid recovery holes 46, and theattraction holes 24, is separated from the gas (air), and the liquid istemporarily accumulated in the first tank 27 and the second tank 31respectively. The gas/liquid separation avoids the inflow of the liquidinto the vacuum pumps 29, 33 as the vacuum sources. Thus, it is possibleto prevent the vacuum pumps 29, 33 from being damaged. Discharge passage27A, 31A are provided for the first and second tanks 27, 31respectively. When predetermined amounts of the liquid are stored asdetected by a water level sensor or the like, the liquid is dischargedfrom the discharge passages 27A, 31A.

Alternatively, a flow passage, which is different from the flow passage22 (tank 27, valve 28, vacuum pump 29) connected to the liquid-absorbingmember 21 (groove 23), may be provided to make connection to the liquidrecovery holes 46. In FIG. 5, a movement mirror 54X, which extends inthe Y axis direction, is provided at the end of the Z stage 51 on the +Xside. A movement mirror 54Y, which extends in the X axis direction, isprovided at the end on the Y side. Laser interferometers radiate laserbeams onto the movement mirrors 54X, 54Y to detect the position of thesubstrate stage PST in the X axis direction and the Y axis direction.

Next, an explanation will be made about a procedure for exposing thesubstrate P with the pattern of the mask M by using the exposureapparatus EX described above.

When the mask M is loaded on the mask stage MST, and the substrate P isloaded on the substrate stage PST, then the control unit CONT drives theliquid supply unit 1 and the liquid recovery unit 2 to form the liquidimmersion portion of the liquid 50 in the space 56 (see FIG. 1). Thecontrol unit CONT controls the illumination optical system IL toilluminate the mask M with the exposure light beam EL, and the image ofthe pattern of the mask M is projected onto the substrate P through theprojection optical system PL and the liquid 50. In this situation, theliquid 50, which is supplied from the liquid supply unit 1, is recoveredby the liquid recovery unit 2 during the period in which the shot areadisposed in the vicinity of the center of the substrate P is exposed.Therefore, the liquid 50 does not outflow to the outside of thesubstrate P.

On the other hand, as shown in FIG. 6, when the edge area E of thesubstrate P is subjected to the exposure process, and the liquidimmersion portion between the projection optical system PL and thesubstrate P is thereby disposed in the vicinity of the edge area E ofthe substrate P, then the liquid 50 can be continuously retained betweenthe projection optical system PL and the substrate P by the aid of theauxiliary plate 59. However, a part of the liquid 50 sometimes outflowsto the outside of the auxiliary plate 59. The outflowed fluid 50 isabsorbed (recovered) by the liquid-absorbing member 21. The control unitCONT starts the opening operation of the valve 28 and the drivingoperation of the pump 29 simultaneously with the start of the drivingoperation of the liquid supply unit 1 and the liquid recovery unit 2.Therefore, the liquid 50, which is recovered by the liquid-absorbingmember 21, is sucked and collected into the first tank 27 through theflow passage 22 and the tube passage 26 together with the surroundingair in accordance with the suction effected by the pump 29 as thesuction unit.

The liquid 50, which outflows from the gap between the substrate P andthe auxiliary plate 59, is sucked to the side of the flow passage 22together with the surrounding air through the liquid recovery holes 46provided on the back surface side of the substrate P. The liquid 50 isrecovered into the first tank 27 through the tube passage 26.

Further, there may be the following possibility. That is, the liquid 50,which enters the back surface side of the substrate P via the gapbetween the substrate P and the auxiliary plate 59, may inflow into theattraction holes 24 for attracting and holding the substrate P. Asdescribed above, the attraction holes 24 are connected to the pump 33 asthe suction unit via the flow passage 25, the tube passage 30, and thesecond tank 31. Therefore, when the opening operation of the valve 32and the driving operation of the pump 33 are performed, then thesubstrate P is attracted and held on the Z stage 51, and the liquid 50,which inflows into the attraction holes 24, can be collected into thesecond tank 31 through the flow passage 25 and the tube passage 30. Thatis, the third recovery unit, which recovers the liquid 50 inflowed intothe attraction holes 24, includes the fluid passage 25, the tube passage30, the second tank 31, the valve 32, the pump 33, and the control unitCONT for controlling the driving of these components. In this situation,the attraction holes 24 also function as liquid recovery holes (recoveryunit) provided on the back surface side of the substrate P.

The liquid which has leaked into the back surface side of the substrateP and the gas (air) which is around the back surface of the substrate Pinflow from the attraction holes 24 in the same manner as from theliquid recovery holes 46. However, the liquid (water) and the gas (air)are separated from each other by making the liquid to fall in the secondtank 31. The liquid, which is stored in the second tank 31, isperiodically recovered, and thus the vacuum pump 33 as the vacuum sourceis prevented from the inflow of the liquid. Accordingly, the vacuum pump33 is prevented from being damaged.

When the edge area E of the substrate P is subjected to the exposureprocess, i.e., when the liquid immersion portion between the projectionoptical system PL and the substrate P is disposed in the vicinity of thecircumferential edge of the substrate P, there is such a possibilitythat a part of the liquid 50 may outflow to the outside of the substrateP as described above. In this embodiment, the control unit CONT performsthe following operation in order that the space between the projectionoptical system PL and the substrate P can be sufficiently filled withthe liquid 50 even when the liquid 50 outflows to the outside of thesubstrate P. That is, when the liquid immersion portion is disposed inthe edge area E of the substrate P, the control unit CONT performs atleast any one of the operation in which the liquid supply unit 1 iscontrolled to increase the liquid supply amount per unit time to thespace 56 and the operation in which the liquid recovery unit (secondrecovery unit) 2 is controlled to decrease the liquid recovery amountper unit time from the space 56. In the control to increase the liquidsupply amount or decrease the liquid recovery amount, the control unitCONT may control the liquid supply unit 1 and/or the liquid recoveryunit 2 on the basis of the result of the detection of the position ofthe substrate P performed by the laser interferometer. Alternatively, adetecting unit for detecting the amount of the recovered (outflowed)liquid may be provided, for example, for the first and second tanks 27,32 or the tube passages 26, 30, and the liquid supply unit 1 and/or theliquid recovery unit 2 may be controlled on the basis of the result ofthe detection performed by the detecting unit.

The exposure apparatus EX of this embodiment is a so-called scanningstepper. Therefore, when the scanning exposure is performed by movingthe substrate P in the scanning direction (−X direction) indicated bythe arrow Xa (see FIG. 3), the liquid 50 is supplied and recovered withthe liquid supply unit 1 and the liquid recovery unit 2 by using thesupply tube 3, the supply nozzles 4A to 4C, the recovery tube 6, and therecovery nozzles 5A, 5B. That is, when the substrate P is moved in the−X direction, then the liquid 50 is supplied to the space between theprojection optical system PL and the substrate P from the liquid supplyunit 1 by the aid of the supply tube 3 and the supply nozzles 4 (4A to4C), and the liquid 50 is recovered to the liquid recovery unit 2 by theaid of the recovery nozzles 5 (5A, 5B) and the recovery tube 6. Theliquid 50 flows in the −X direction so that the space between the lens60 and the substrate P is filled therewith. On the other hand, when thescanning exposure is performed by moving the substrate P in the scanningdirection (+X direction) indicated by the arrow Xb, then the liquid 50is supplied and recovered with the liquid supply unit 1 and the liquidrecovery unit 2 by using the supply tube 10, the supply nozzles 8A to8C, the recovery tube 11, and the recovery nozzles 9A, 9B. That is, whenthe substrate P is moved in the +X direction, then the liquid 50 issupplied from the liquid supply unit 1 to the space between theprojection optical system PL and the substrate P by the aid of thesupply tube 10 and the supply nozzles 8 (8A to 8C), and the liquid 50 isrecovered to the liquid recovery unit 2 by the aid of the recoverynozzles 9 (9A, 9B) and the recovery tube 11. The liquid 50 flows in the+X direction so that the space between the lens 60 and the substrate Pis filled therewith. As described above, the control unit CONT makes theliquid 50 to flow in the movement direction of the substrate P by usingthe liquid supply unit 1 and the liquid recovery unit 2. In thisarrangement, for example, the liquid 50, which is supplied from theliquid supply unit 1 through the supply nozzles 4, flows so that theliquid 50 is attracted and introduced into the space 56 in accordancewith the movement of the substrate P in the −X direction. Therefore,even when the supply energy of the liquid supply unit 1 is small, theliquid 50 can be supplied to the space 56 with ease. When the direction,in which the liquid 50 is made to flow, is switched depending on thescanning direction, then it is possible to fill the space between thesubstrate P and the tip surface 7 of the lens 60 with the liquid 50, andit is possible to obtain the high resolution and the wide depth offocus, even when the substrate P is subjected to the scanning in any oneof the +X direction and the −X direction.

As explained above, even when the liquid 50 outflows to the outside ofthe substrate P, the outflowed liquid 50 is recovered by the recoveryunit 20 without being left to stand. Therefore, the variation of theenvironment in which the substrate P is placed is suppressed, and theoccurrence of the inconvenience is also suppressed, which would beotherwise caused such that any rust or the like appears on mechanicalparts disposed around the substrate stage PST for supporting thesubstrate P. Therefore, the pattern can be accurately transferred to thesubstrate P, and it is possible to produce a device having a highpattern accuracy.

The liquid-absorbing member 21 is provided as the recovery unit 20 onthe substrate stage PST, and thus the liquid 50 can be reliably retained(recovered) over a wide range. Further, the pump 29, which serves as thesuction unit, is connected to the liquid-absorbing member 21 via theflow passage, and thus the liquid 50, which is absorbed by theliquid-absorbing member 21, is always discharged to the outside of thesubstrate stage PST. Therefore, it is possible to more reliably suppressthe variation of the environment in which the substrate P is placed, andit is possible to suppress the variation of the weight of the substratestage PST, which would be otherwise caused by the liquid 50.Alternatively, the following procedure is also available. That is, thepump 29 is stopped during the exposure for the substrate, and the liquid50, which is outflowed to the outside of the substrate P, is retained,for example, by the liquid-absorbing member 21. The pump 29 is operatedafter the completion of the exposure for the substrate so that theliquid is discharged. On the other hand, the following arrangement isalso available. That is, the liquid 50, which is recovered by theliquid-absorbing member 21, is discharged in an untreated manner towardthe tank 27 in accordance with the self-weight without providing thepump 29. Further, the following arrangement is also available. That is,the pump 29, the tank 27, and the flow passage are not provided, andonly the liquid-absorbing member 21 is arranged on the substrate stagePST. The liquid-absorbing member 21, which has absorbed the liquid 50,is exchanged periodically (for example, for every one lot). In thisarrangement, the weight of the substrate stage PST is varied by theliquid 50. However, the stage positioning accuracy can be maintained bychanging the stage control parameter depending on the weight of theliquid 50 recovered by the liquid-absorbing member 21.

The tanks 27, 31, which are used to separate the liquid (water) and thegas (air) from each other, are provided at the upstream of the vacuumpumps 29, 33 to avoid any inflow of the liquid into the vacuum pumps 29,33. Therefore, the vacuum pumps 29, 33 can be prevented from beingbroken down and damaged.

The vacuum pumps 29, 33 in the embodiment described above may bearranged in the exposure apparatus EX. Alternatively, it is alsoallowable to use those installed in a factory in which the exposureapparatus EX is installed. In the embodiment described above, the tank,which is used to separate the liquid (water) and the gas (air) from eachother, is provided for the vacuum system of the recovery unit 20 (at theupstream of the vacuum pump) for recovering the liquid outflowed to theoutside of the substrate P and for the vacuum system for attracting andholding the substrate P. However, there is no limitation thereto inrelation to the installation of the mechanism (for example, the tank forrecovering the liquid) for separating the liquid (water) and the gas(air) from each other. Such a mechanism may be provided in the suctionsystem (vacuum system) connected to any other suction port for which itis feared that the liquid may make any inflow. For example, such amechanism may be arranged in a gas recovery system (suction system) fora gas bearing, a suction system for attracting and holding the substrateP on a substrate transport arm, or a suction system for detachablyattracting and holding a substrate-holding member on the substratestage. The gas recovery system (suction system) for the gas bearing isdisclosed, for example, in Japanese Patent Application Laid-open No.11-166990, the suction system for attracting and holding the substrate Pon the substrate transport arm is disclosed, for example, in JapanesePatent Application Laid-open No. 6-181157, and the suction system fordetachably attracting and holding the substrate-holding member on thesubstrate stage is disclosed, for example, in Japanese PatentApplication Laid-open No. 10-116760. The contents of the descriptions inthese documents are incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application. In this embodiment, themechanism, which includes, for example, the tank for separating theliquid (water) and the gas (air) from each other, is applied to theexposure apparatus in which the substrate P is subjected to the exposurewhile forming the liquid immersion portion in a part of the area on thesubstrate P. However, the present invention is also applicable to anexposure apparatus in which a substrate stage is moved in a liquid tank,and an exposure apparatus in which a liquid tank is formed on asubstrate stage and a substrate is held therein. The structure and theexposure operation of the exposure apparatus in which the substratestage is moved in the liquid tank are disclosed, for example, inJapanese Patent Application Laid-open No. 6-124873, and the exposureapparatus in which the liquid tank is formed on the substrate stage andthe substrate is held therein is disclosed, for example, in JapanesePatent Application Laid-open No. 10-303114 and U.S. Pat. No. 5,825,043.The contents of the descriptions in these documents are incorporatedherein by reference within a range of permission of the domestic lawsand ordinances of the state designated or selected in this internationalapplication.

In the embodiment described above, the liquid-absorbing member 21 isformed to have the annular form which continues to surround the entirecircumference of the substrate P. However, the liquid-absorbing member21 may be arranged at a part of the circumference of the substrate P.Alternatively, the liquid-absorbing member 21 may be arrangeddiscontinuously at predetermined intervals. In this embodiment, theliquid-absorbing member 21 is formed to have the annular form. However,the shape of the liquid-absorbing member 21 may be, for example,rectangular, which may be arbitrarily designed.

The arrangement of the liquid supply unit 1 and the liquid recovery unit2 and the arrangement of the nozzles are not limited to those describedin the foregoing embodiment. It is not necessarily indispensable thatthe liquid supply unit 1 and the liquid recovery unit 2 are operatedconcurrently during the exposure for the substrate P. Any one of themmay be stopped or both of them may be stopped provided that the opticalpath for the exposure light beam, which is disposed between theprojection optical system PL and the substrate P, is filled with theliquid 50.

As described above, pure water is used as the liquid 50 in thisembodiment. Pure water is advantageous in that pure water is availablein a large amount with ease, for example, in the semiconductorproduction factory, and pure water exerts no harmful influence, forexample, on the optical element (lens) and the photoresist on thesubstrate P. Further, pure water exerts no harmful influence on theenvironment, and the content of impurity is extremely low. Therefore, itis also expected to obtain the function to wash the surface of thesubstrate P and the surface of the optical element provided at the tipsurface of the projection optical system PL.

It is approved that the refractive index n of pure water (water) withrespect to the exposure light beam EL having a wavelength of about 193nm is approximately in an extent of 1.44 to 1.47. When the ArF excimerlaser beam (wavelength: 193 nm) is used as the light source of theexposure light beam EL, then the wavelength is shortened on thesubstrate P by 1/n, i.e., to about 131 to 134 nm, and a high resolutionis obtained. Further, the depth of focus is magnified about n times,i.e., about 1.44 to 1.47 times as compared with the value obtained inthe air. Therefore, when it is enough to secure an approximatelyequivalent depth of focus as compared with the case of the use in theair, it is possible to further increase the numerical aperture of theprojection optical system PL. Also in this viewpoint, the resolution isimproved.

In this embodiment, the lens 60 is attached to the tip of the projectionoptical system PL. However, the optical element, which is attached tothe tip of the projection optical system PL, may be an optical platewhich is usable to adjust the optical characteristics of the projectionoptical system PL, for example, the aberration (for example, sphericalaberration and comatic aberration). Alternatively, the optical elementmay be a parallel plane plate through which the exposure light beam ELis transmissive. When the optical element, which makes contact with theliquid 50, is the parallel plane plate which is cheaper than the lens,it is enough that merely the parallel plane plate is exchangedimmediately before supplying the liquid 50 even when any substance (forexample, any silicon-based organic matter), which deteriorates thetransmittance of the projection optical system PL, the illuminance ofthe exposure light beam EL on the substrate P, and the uniformity of theilluminance distribution, is adhered to the parallel plane plate, forexample, during the transport, the assembling, and/or the adjustment ofthe exposure apparatus EX. An advantage is obtained such that theexchange cost is lowered as compared with the case in which the opticalelement to make contact with the liquid 50 is the lens. That is, thesurface of the optical element to make contact with the liquid 50 isdirtied, for example, due to the adhesion of scattered particlesgenerated from the resist by being irradiated with the exposure lightbeam EL or any impurity contained in the liquid 50. Therefore, it isnecessary to periodically exchange the optical element. However, whenthe optical element is the cheap parallel plane plate, then the cost ofthe exchange part is low as compared with the lens, and it is possibleto shorten the time required for the exchange. Thus, it is possible tosuppress the increase in the maintenance cost (running cost) and thedecrease in the throughput.

When the pressure, which is generated by the flow of the liquid 50, islarge between the substrate P and the optical element disposed at thetip of the projection optical system PL, it is also allowable that theoptical element is tightly fixed so that the optical element is notmoved by the pressure, rather than allowing the optical element to beexchangeable.

The liquid 50 is water in the embodiment described above. However, theliquid 50 may be any liquid other than water. For example, when thelight source of the exposure light beam EL is the F₂ laser, the F₂ laserbeam is not transmitted through water. Therefore, in this case, thosepreferably usable as the liquid 50 may include, for example,fluorine-based liquids such as fluorine-based oil and fluoropolyether(PFPE) through which the F₂ laser beam is transmissive. Alternatively,other than the above, it is also possible to use, as the liquid 50,those (for example, cedar oil) which have the transmittance with respectto the exposure light beam EL, which have the refractive index as highas possible, and which are stable against the photoresist applied to thesurface of the substrate P and the projection optical system PL.

Second Embodiment

Next, an explanation will be made with reference to FIG. 7 about anotherembodiment of the exposure apparatus EX of the present invention. In thefollowing description, the same or equivalent constitutive parts asthose of the embodiment described above are designated by the samereference numerals, any explanation of which is simplified or omitted.The characteristic features of this embodiment are that a liquidrecovery groove 35 is provided around the substrate P in place of theliquid-absorbing member 21 as the recovery unit and that the substratestage PST and the tube passage 26 are connectable to one another andseparable from each other.

With reference to FIG. 7, the recovery unit 20 includes the liquidrecovery groove 35 which has a predetermined width and which is formedaround the auxiliary plate 59 on the Z stage 51. A connecting valve 36is provided at the end of the flow passage 22. On the other hand, aconnecting valve 37, which is connectable and separable with respect tothe connecting valve 36, is provided at the end of the tube passage 26.In a state in which the connecting valves 36, 37 are separated from eachother, the end of the flow passage 22 is closed so that the fluid 50does not outflow to the outside of the stage. On the other hand, whenthe connecting valves 36, 37 are connected to each other, then the endof the flow passage 22 is opened, and the liquid 50 in the flow passage22 can flow to the tube passage 26.

During the exposure process, the connecting valve 36 is separated fromthe connecting valve 37. Therefore, the substrate stage PST is in astate of being separated from the tube passage 26 during the exposureprocess. Therefore, it is possible to smoothly perform the movement inthe scanning direction (scanning movement) and the movement in thenon-scanning direction (stepping movement). The liquid 50, whichoutflows to the outside of the substrate P during the exposure process,is pooled or stored in the liquid recovery groove 35 and the flowpassage 22.

When the exposure process is completed, the substrate stage PST is movedto the exchange position for the substrate P (load/unload position). Theconnecting valves 36, 37 are connected to each other at the substrateexchange position. When the connecting valves 36, 37 are connected toeach other, then the control unit CONT opens the valve 28, and thecontrol unit CONT drives the pump 29. Accordingly, the liquid 50, whichhas been recovered by the liquid recovery groove 35 as the recoveryunit, is discharged to the outside of the stage at the substrateexchange position.

This embodiment is constructed such that the liquid 50 recovered by theliquid recovery groove 35 is discharged to the outside of the stageperiodically (for example, for every one lot). Therefore, the liquidrecovery groove 35 is designed to have, for example, a size (volume) ofsuch an extent that the liquid, which corresponds to the amount ofoutflow of one lot, can be retained. In this arrangement, therelationship between a predetermined number of the substrates to besubjected to the exposure process (i.e., corresponding to one lot) andthe amount of the liquid to be outflowed is previously determined. Thesize of the liquid recovery groove 35 is set on the basis of thedetermined relationship. Further, the time interval for connecting theconnecting valves 36, 37 (i.e., the timing to perform the operation fordischarging the liquid to the outside of the stage) is set on the basisof the determined relationship described above.

In the embodiment described above, the liquid recovery groove 35 isformed to have the annular form which continues to surround the entirecircumference of the substrate P. However, the liquid recovery groove 35may be arranged at a part of the circumference of the substrate P.Alternatively, the liquid recovery groove 35 may be arrangeddiscontinuously at predetermined intervals. In this embodiment, theliquid recovery groove 35 is formed to have the annular form. However,the shape of the liquid recovery groove 35 may be, for example,rectangular, which may be arbitrarily designed. Further, theliquid-absorbing member may be arranged in the liquid recovery groove35.

In the respective embodiments described above, the auxiliary plate 59 isprovided at the outside of the substrate P. However, theliquid-absorbing member 21 and/or the liquid recovery groove 35 may beprovided at the position in the vicinity of the outer circumference ofthe substrate P without providing the auxiliary plate 59.

The embodiment described above adopts the exposure apparatus in whichthe space between the projection optical system PL and the substrate Pis locally filled with the liquid. However, the recovery mechanism ofthe present invention, which recovers the liquid inflowed into theattraction holes for attracting and holding the substrate P as disclosedin FIGS. 6 and 7, is also applicable to the liquid immersion exposureapparatus in which the stage for holding the exposure objectivesubstrate is moved in the liquid tank and the liquid immersion exposureapparatus in which the liquid tank having the predetermined depth isformed on the stage and the substrate is held therein. As describedabove, the structure and the exposure operation of the liquid immersionexposure apparatus in which the stage holding the exposure objectivesubstrate is moved in the liquid tank are disclosed, for example, inJapanese Patent Application Laid-open No. 6-124873, and the structureand the exposure operation of the liquid immersion exposure apparatus inwhich the liquid tank having the predetermined depth is formed on thesubstrate stage and the substrate is held therein are disclosed, forexample, in Japanese Patent Application Laid-open No. 10-303114(corresponding to U.S. Pat. No. 5,825,043).

Third Embodiment

An explanation will be made below with reference to FIGS. 8 to 10 aboutanother embodiment of the recovery unit.

As shown in FIG. 8, the upper surface of the Z stage 51 is inclined, andthe upper surface of the holder 57 for holding the substrate P ishorizontal. A liquid recovery groove 35 is formed to surround thecircumference of the holder 57. In this arrangement, the liquid recoverygroove 35 is annular as viewed in a plan view, but the liquid recoverygroove 35 is inclined as viewed in a side view. That is, the liquidrecovery groove 35 is arranged along the inclination of the uppersurface of the Z stage 51. Accordingly, the liquid 50, which outflows tothe outside of the substrate P, is spontaneously pooled at an inclinedlower section 35A of the liquid recovery groove 35. Accordingly, it iseasy to perform the recovery operation for recovering liquid 50 byrecovering only the liquid 50 pooled at the inclined lower section 35A.

As shown in FIG. 9A, the liquid recovery groove 35 is provided at a partof the upper surface of the Z stage 51. When the exposure process isperformed, the liquid 50 is pooled in the liquid recovery groove 35. Asshown in FIG. 9B, the liquid 50, which is pooled in the liquid recoverygroove 35, is recovered through a tube 38 which is attached to atransport unit H for loading/unloading the substrate P with respect tothe substrate stage PST. A tube 38, which constitutes a part of thesuction unit, sucks the liquid 50 pooled in the liquid recovery groove35 when the transport unit H makes the access with respect to thesubstrate stage PST in order that the substrate P, for which theexposure process has been completed, is unloaded from the substratestage PST.

Fourth Embodiment

An explanation will be made below about still another embodiment of therecovery unit. As shown in FIG. 10A, the liquid recovery groove 35 isprovided on the upper surface of the Z stage 51. The liquid recoverygroove 35 is connected to a flow passage 39 which penetrates to thelower surface side of the Z stage 51. A valve 39A is provided in theflow passage 39. Flow passages 40, 41 as through-holes are formedthrough the XY stage 52 and the base 53 respectively corresponding tothe flow passage 39 of the Z stage 51. The valve 39A is closed duringthe exposure process, and the liquid 50 is pooled in the liquid recoverygroove 35 as shown in FIG. 10A. When the exposure process is completed,then the control unit CONT moves the substrate stage PST to thesubstrate exchange position, and the valve 39A is opened. Accordingly,as shown in FIG. 10B, the liquid 50 contained in the liquid recoverygroove 35 is discharged to the outside of the stage in accordance withthe self-weight at the substrate exchange position through the flowpassages 39, 40, 41. It is preferable that the liquid 50 contained inthe liquid recovery groove 35 is recovered at the substrate exchangeposition. However, it is also allowable that the discharge operation isperformed at any positions other than the substrate exchange position.

Fifth Embodiment

In the respective embodiments described above, the liquid immersion areais formed on a part of the substrate P such that the liquid supply unit1 supplies the liquid 50 onto the substrate P above the substrate P(from above the substrate P) by the aid of the supply nozzles 4, and theliquid recovery unit 2 as the second recovery unit recovers the liquid50 disposed on the substrate P above the substrate P by the aid of therecovery nozzles 5. However, as shown in FIG. 11, almost all of theliquid 50 supplied onto the substrate P may be recovered by using therecovery unit 20 provided in the substrate stage PST, without providingthe liquid recovery unit 2 (recovery nozzles 5) above the substrate P.FIG. 11 shows the supply nozzles 4, 8 which are provided on the bothsides of the projection area (optical element 60) of the projectionoptical system PL, so that the projection area 60 is intervened betweenthe supply nozzles 4, 8 in the scanning direction. When the liquid 50 issupplied in order to perform the scanning exposure for the substrate P,then the liquid 50 may be supplied from any one of the supply nozzles ofthe supply nozzles 4, 8, depending on the direction of movement of thesubstrate P or the liquid 50 may be supplied simultaneously from theboth supply nozzles 4, 8. The liquid 50, which is supplied from theliquid supply unit 1, is widely spread on the substrate P, making itpossible to form a large liquid immersion area. As shown in aperspective view of FIG. 12, the liquid 50 supplied onto the substrate Poutflows to the outside of the substrate P soon. However, almost all ofthe liquid 50 is recovered by the recovery unit 20 having the groove 23(liquid-absorbing member 21) provided as the recovery port around thesubstrate P. In this arrangement, the liquid immersion area can beformed on the substrate P in a well-suited manner by continuing thesupply of the liquid 50 onto the substrate P by the liquid supply unit 1during the exposure process for the substrate P. Further, it is possibleto create the flow of the fluid 50 on the substrate P owing to thesupplied liquid 50. Therefore, it is possible to always supply the flesh(clean) liquid 50 onto the substrate P, and it is possible to make theliquid 50 on the substrate P to flow to arrive at the groove 23.

The liquid recovery unit 2 as the second liquid recovery unit isconstructed such that the liquid 50 on the substrate P is sucked andrecovered by using the vacuum system above the substrate P by the aid ofthe recovery nozzles 5. The liquid (water) and the gas (air) arerecovered together. Therefore, the liquid hits, for example, against theinner wall of the recovery tube 6, and the sound and/or the vibrationappears in some cases. In such a situation, as in the embodiment shownin FIGS. 11 and 12, the liquid 50 is recovered by using only therecovery unit 20 provided for the substrate stage PST without performingthe suction and recovery above the substrate P. Accordingly, it ispossible to avoid the occurrence of the sound and the vibration duringthe exposure for the substrate P.

In the case of this embodiment in which the liquid is not recoveredabove the substrate P, the mechanism shown in FIG. 7 in the secondembodiment may be used as the recovery unit 20. In the case of FIG. 7,the vacuum pump 29 does not suck the liquid recovered by the liquidrecovery groove 35 during the exposure for the substrate P. Therefore,it is also possible to suppress the occurrence of the sound and thevibration associated with the suction of the liquid, which is moreeffective.

Further, the following procedure is also available as in the embodimentexplained above. That is, the liquid recovery unit 2, which recovers theliquid through the recovery nozzles 5 above the substrate P, isarranged. The liquid is recovered by using only the recovery unit 20without operating the liquid recovery unit 2 during the exposure for thesubstrate P. The liquid 50 is recovered by using the liquid recoveryunit 2 and the recovery unit 20 in combination after the completion ofthe exposure for the substrate P. Also in this case, it is possible tosuppress the influence of the sound and the vibration associated withthe suction (recovery) of the liquid during the exposure for thesubstrate P.

The substrate P, which is usable in the respective embodiments describedabove, is not limited to the semiconductor wafer for producing thesemiconductor device. Those applicable include, for example, the glasssubstrate for the display device, the ceramic wafer for the thin filmmagnetic head, and the master plate (synthetic quartz, silicon wafer)for the mask or the reticle to be used for the exposure apparatus.

As for the exposure apparatus EX, the present invention is alsoapplicable to the scanning type exposure apparatus (scanning stepper)based on the step-and-scan system for performing the scanning exposurefor the pattern of the mask M by synchronously moving the mask M and thesubstrate P as well as the projection exposure apparatus (stepper) basedon the step-and-repeat system for performing the full field exposure forthe pattern of the mask M in a state in which the mask M and thesubstrate P are made to stand still, while successively step-moving thesubstrate P. The present invention is also applicable to the exposureapparatus based on the step-and-stitch system in which at least twopatterns are partially overlaid and transferred on the substrate P.

As for the type of the exposure apparatus EX, the present invention isnot limited to the exposure apparatus for the semiconductor productionapparatus for exposing the substrate P with the semiconductor devicepattern. The present invention is also widely applicable, for example,to the exposure apparatus for producing the liquid crystal displaydevice or for producing the display as well as the exposure apparatusfor producing, for example, the thin film magnetic head, the imagepickup device (CCD), the reticle, or the mask.

The present invention is also applicable to a twin-stage type exposureapparatus. The structure and the exposure operation of the twin-stagetype exposure apparatus are disclosed, for example, in documents ofJapanese Patent Application Laid-open Nos. 10-163099 and 10-214783,Published Japanese translation of PCT International Publication forPatent Application No. 2000-505958, and U.S. Pat. Nos. 6,341,007,6,400,441, 6,549,269, and 6,590,634. Reference may be made thereto.These United States Patents are incorporated herein by reference withina range of permission of the domestic laws and ordinances of the statedesignated or selected in this international application.

When the linear motor is used for the substrate stage PST and/or themask stage MST, it is allowable to use any one of those of the airfloating type based on the use of the air bearing and those of themagnetic floating type based on the use of the Lorentz's force or thereactance force. Each of the stages PST, MST may be either of the typein which the movement is effected along the guide or of the guidelesstype in which no guide is provided. An example of the use of the linearmotor for the stage is disclosed in U.S. Pat. Nos. 5,623,853 and5,528,118. The contents of the descriptions in the documents areincorporated herein by reference respectively within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

As for the driving mechanism for each of the stages PST, MST, it is alsoallowable to use a plane motor in which a magnet unit provided withtwo-dimensionally arranged magnets and an armature unit provided withtwo-dimensionally arranged coils are opposed to each other, and each ofthe stages PST, MST is driven by the electromagnetic force. In thisarrangement, any one of the magnet unit and the armature unit isconnected to the stage PST, MST, and the other of the magnet unit andthe armature unit is provided on the side of the movable surface of thestage PST, MST.

The reaction force, which is generated in accordance with the movementof the substrate stage PST, may be mechanically released to the floor(ground) by using a frame member so that the reaction force is nottransmitted to the projection optical system PL. The method for handlingthe reaction force is disclosed in detail, for example, in U.S. Pat. No.5,528,118 (Japanese Patent Application Laid-open No. 8-166475). Thecontents of the descriptions in the documents are incorporated herein byreference within a range of permission of the domestic laws andordinances of the state designated or selected in this internationalapplication.

The reaction force, which is generated in accordance with the movementof the mask stage MST, may be mechanically released to the floor(ground) by using a frame member so that the reaction force is nottransmitted to the projection optical system PL. The method for handlingthe reaction force is disclosed in detail, for example, in U.S. Pat. No.5,874,820 (Japanese Patent Application Laid-open No. 8-330224). Thecontents of the descriptions in the documents are incorporated herein byreference within a range of permission of the domestic laws andordinances of the state designated or selected in this internationalapplication.

As described above, the exposure apparatus EX according to theembodiment of the present invention is produced by assembling thevarious subsystems including the respective constitutive elements asdefined in claims so that the predetermined mechanical accuracy, theelectric accuracy, and the optical accuracy are maintained. In order tosecure the various accuracies, those performed before and after theassembling include the adjustment for achieving the optical accuracy forthe various optical systems, the adjustment for achieving the mechanicalaccuracy for the various mechanical systems, and the adjustment forachieving the electric accuracy for the various electric systems. Thesteps of assembling the various subsystems into the exposure apparatusinclude, for example, the mechanical connection, the wiring connectionof the electric circuits, and the piping connection of the air pressurecircuits in correlation with the various subsystems. It goes withoutsaying that the steps of assembling the respective individual subsystemsare performed before performing the steps of assembling the varioussubsystems into the exposure apparatus. When the steps of assembling thevarious subsystems into the exposure apparatus are completed, theoverall adjustment is performed to secure the various accuracies as theentire exposure apparatus. It is desirable that the exposure apparatusis produced in a clean room in which, for example, the temperature andthe cleanness are managed.

As shown in FIG. 13, the microdevice such as the semiconductor device isproduced by performing, for example, a step 201 of designing thefunction and the performance of the microdevice, a step 202 ofmanufacturing a mask (reticle) based on the designing step, a step 203of producing a substrate as a base material for the device, an exposureprocess step 204 of exposing the substrate with a pattern of the mask byusing the exposure apparatus EX of the embodiment described above, astep 205 of assembling the device (including a dicing step, a bondingstep, and a packaging step), and an inspection step 206.

According to the present invention, even when the liquid outflows, theliquid is recovered by the recovery unit without being left to stand.Therefore, it is possible to avoid the inconvenience resulting from theoutflowed liquid, and it is possible to produce the device having thehigh pattern accuracy.

1. A lithographic apparatus comprising: an illumination system whichprovides a beam of radiation; a support structure which holds apatterning device; a substrate table which holds a substrate; aprojection system which projects the patterned beam onto a targetportion of the substrate; a liquid supply system which provides animmersion liquid to a space between the substrate and the projectionsystem such that only a localized area of the substrate is covered bythe immersion liquid, the localized area having a size which is smallerthan that of a surface of the substrate on which the localized area isformed; an inlet which supplies the immersion liquid, the inlet notbeing provided on the substrate table; and a first outlet which removesthe immersion liquid, the first outlet being provided on the substratetable to be positioned adjacent to a periphery of the substrate; and asecond outlet which removes the immersion liquid, the second outletbeing provided on the substrate table to be positioned on an outer sideof the first outlet with respect to the substrate, wherein no seal isprovided to constrain the immersion liquid in the space.
 2. An apparatusaccording to claim 1, wherein the inlet is provided above the substratetable.
 3. A device manufacturing method comprising: projecting apatterned beam of radiation onto a target portion of a substrate using aprojection system; providing an immersion liquid to a space between thesubstrate on a substrate table and the projection system using an inletnot provided on the substrate table such that only a localized area ofthe substrate is covered by the immersion liquid, the localized areahaving a size which is smaller than that of a surface of the substrateon which the localized area is formed; allowing the immersion liquid toleak from the space; removing the immersion liquid through a firstoutlet positioned on the substrate table; and removing the immersionliquid through a second outlet positioned on an outer side of the firstoutlet with respect to the substrate.
 4. A device manufacturing methodaccording to claim 3, wherein the inlet is provided above the substratetable.
 5. A lithographic apparatus comprising: an illumination systemwhich provides a beam of radiation; a support structure which holds apatterning device; a substrate table which holds a substrate; aprojection system which projects the patterned beam onto a targetportion of the substrate; a liquid supply system which provides animmersion liquid to a space between the substrate and the projectionsystem such that only a localized area of the substrate is covered bythe immersion liquid, the localized area having a size which is smallerthan that of a surface of the substrate on which the localized area isformed, the liquid supply system comprising an immersion liquid inletport provided at a boundary of the space, the immersion liquid inletport not being provided on the substrate table; a first immersion liquidoutlet port provided on the substrate table, the first immersion liquidoutlet port being positioned adjacent to an outer peripheral edge of thesubstrate; and a second immersion liquid outlet port provided on thesubstrate table, the second immersion liquid outlet port beingpositioned on an outer side of the first immersion liquid outlet portwith respect to the substrate, wherein the immersion liquid is notsubstantially confined in the space so that immersion liquid can flowout of the space.
 6. An apparatus according to claim 5, wherein theimmersion liquid inlet port is provided above the substrate table.
 7. Alithographic apparatus comprising: an illuminator which provides a beamof radiation; a support structure which holds a patterning device; asubstrate table which holds a substrate; a projection system whichprojects the patterned beam onto a target portion of the substrate; anda liquid supply system which supplies a liquid such that only alocalized area of the substrate, or a localized area of the substrateand the substrate table is covered by the liquid to at least partly filla space between the projection system and the substrate, or thesubstrate and the substrate table, wherein the localized area has a sizewhich is smaller than that of a surface of the substrate on which thelocalized area is formed, wherein the substrate table comprises a firstcollecting portion which collects the liquid, the first collectingportion being positioned adjacent to an outer peripheral edge of thesubstrate, and a second collecting portion which collects the liquid,the second collecting portion surrounding and spaced apart from thesubstrate and the first collecting portion, and wherein the secondcollecting portion comprises a groove recessed into an upper surface ofthe substrate table.
 8. The apparatus of claim 7, wherein the grooveforms a continuous loop.
 9. A lithographic apparatus comprising: anilluminator which provides a beam of radiation; a support structurewhich holds a patterning device; a substrate table which holds asubstrate; a projection system which projects the patterned beam onto atarget portion of the substrate; a liquid supply system which supplies aliquid such that only a localized area of the substrate, or a localizedarea of the substrate and the substrate table is covered by the liquidto at least partly fill a space between the projection system and thesubstrate, or the substrate and the substrate table, wherein thelocalized area has a size which is smaller than that of a surface of thesubstrate on which the localized area is formed, and wherein thesubstrate table comprises a first collecting portion which collects theliquid, the first collecting portion being positioned adjacent to anouter peripheral edge of the substrate, and a second collecting portionwhich collects the liquid, the second collecting portion surrounding andspaced apart from the substrate and the first collecting portion; and asuction supply which removes liquid from at least one of the firstcollecting portion and the second collecting portion.
 10. The apparatusof claim 9, wherein the suction supply comprises a plurality of discreteoutlets.
 11. The apparatus of claim 9, wherein the suction supplyoperates independently of the liquid supply system.
 12. A lithographicapparatus comprising: an illuminator which provides a beam of radiation;a support structure which holds a patterning device; a substrate tablewhich holds a substrate; a projection system which projects thepatterned beam onto a target portion of the substrate; and a liquidsupply system which supplies a liquid to a localized area of thesubstrate, or the substrate and the substrate table to at least partlyfill a space between the projection system and the substrate, or thesubstrate and the substrate table, wherein the substrate table comprisesa barrier which collects liquid, the barrier surrounding and spacedapart from the substrate, wherein the barrier is positioned radiallyoutwardly of a drainage ditch or outlet surrounding an outer peripheraledge of the substrate.
 13. A lithographic apparatus comprising: anilluminator which provides a beam of radiation; a support structurewhich holds a patterning device; a substrate table which holds asubstrate; a projection system which projects the patterned beam onto atarget portion of the substrate; and a liquid supply system whichsupplies a liquid such that only a localized area of the substrate, or alocalized area of the substrate and the substrate table is covered bythe liquid to at least partly fill a space between the projection systemand the substrate, or the substrate and the substrate table, wherein thelocalized area has a size which is smaller than that of a surface of thesubstrate on which the localized area is formed, and wherein thesubstrate table comprises a first collecting portion which collects theliquid, the first collecting portion being positioned adjacent to anouter peripheral edge of the substrate, and a second collecting portionwhich collects the liquid, the second collecting portion surrounding andspaced apart from the substrate and the first collecting portion,wherein the second collecting portion extends substantially around anouter edge or portion of the substrate table.
 14. A lithographicapparatus comprising: an illuminator which provides a beam of radiation;a support structure which holds a patterning device; a substrate tablewhich holds a substrate; a projection system which projects thepatterned beam onto a target portion of the substrate; and a liquidsupply system which supplies a liquid such that only a localized area ofthe substrate, or a localized area of the substrate and the substratetable is covered by the liquid to at least partly fill a space betweenthe projection system and the substrate, or the substrate and thesubstrate table, wherein the localized area has a size which is smallerthan that of a surface of the substrate on which the localized area isformed, and wherein the substrate table comprises a liquid collectingportion which collects the liquid, the liquid collecting portionsurrounding and spaced apart from the substrate, wherein the liquidcollecting portion additionally surrounds areas of an upper surface ofthe substrate table which are not covered by the substrate.
 15. A devicemanufacturing method comprising: providing a liquid such that only alocalized area of a substrate, or a localized area of the substrate anda substrate table is covered by the liquid to at least partly fill aspace between a projection system and the substrate, or the substrateand the substrate table, the localized area having a size which issmaller than that of a surface of the substrate on which the localizedarea is formed; projecting a patterned beam of radiation through theliquid onto a target portion of the substrate using the projectionsystem; collecting the liquid at an outer peripheral edge of thesubstrate with a first collecting portion provided on the substratetable; and collecting the liquid at an outer side of the firstcollecting portion with respect to the substrate with a secondcollecting portion provided on the substrate table.
 16. The devicemanufacturing method according to claim 15, further comprising: removingthe liquid from at least one of the first collecting portion and thesecond collecting portion using a suction supply.
 17. The method ofclaim 16, wherein the removing of the liquid operates independently ofproviding the liquid.
 18. A device manufacturing method comprising:providing a liquid to a localized area of a substrate, or the substrateand a substrate table to at least partly fill a space between aprojection system and the substrate, or the substrate and the substratetable; projecting a patterned beam of radiation through the liquid ontoa target portion of the substrate using the projection system;collecting liquid with a barrier, the barrier surrounding and spacedapart from the substrate; and removing liquid using a drainage ditch oroutlet surrounding an outer peripheral edge of the substrate andpositioned radially inwardly of the barrier.